System and method for analyzing brain activity

A processing method for analyzing brain activity of a subject during a transition between brain states, the processing method comprising:

• receive, from a brain monitoring system for monitoring brain activity, brain activity data of the subject obtained during a transition of the subject from a first brain state to a second brain state of the subject, wherein at least one of the first brain state and/or the second brain state is a sleep state;
• receive from a sensory and monitoring unit adapted to detect a transition of the subject from the first brain state to the second brain state of the subject, information corresponding to the detected transition;
• process the brain activity data and the information from the sensory and monitoring unit to obtain a value for one or more transition parameters of the brain activity data, a transition parameter being a parameter representative of the transition,
• wherein the one or more transition parameters comprise at least one of:
• a transition timing, wherein a transition timing is a length of time between a time at which a transition is detected in the subject by the sensory and monitoring unit and a time at which changes in neuronal networks, identifiable in the subject's brain activity data, responsive to the change in sleep state are first detected a transition duration, wherein a transition duration is a duration from a moment at which a neuronal network associated with the first brain state of the subject starts to become weaker to a moment at which a neuronal network associated with the second brain state becomes fully established;
• a transition stability, wherein a transition stability is a number of transitions between neuronal networks in the brain activity data from a moment at which activity in neuronal networks associated with the first brain state starts to become weaker to a moment at which a network associated with the second brain state becomes fully established;
• and/or
• a frequency of transition, wherein a frequency of transition is a measure of the number of times a transition from the first brain state to the second brain state occurs in a set time period;
• and
• process the values of the one or more transition parameters of the brain activity data and corresponding values of the one or more transition parameters for a plurality of groups of subjects to identify which of the plurality of groups the subject most closely resembles, wherein the plurality of groups of subjects comprises at least a first group and a second group, wherein the first group comprises healthy subjects and the second group comprises subjects having a mental disorder.